Doxycycline
Doxycycline
Doxycycline is a tetracycline-class antibiotic that has recently gained recognition as an effective post-exposure prophylaxis (PEP) strategy against sexually transmitted infections (STIs). Known as Doxy-PEP, this therapy involves taking doxycycline after condomless sex to reduce the risk of acquiring chlamydia, syphilis, and gonorrhea. Clinical studies have shown that Doxy-PEP significantly lowers STI rates in high-risk individuals, especially men who have sex with men (MSM) and transgender women. It is taken within 72 hours of sexual exposure.
How does it work?
Frequently asked question
What can I expect with Doxycycline treatment?
• Take 1 dose of 200mg doxycycline (usually two 100mg tablets) within 72 hours of condomless sex
• Best used under guidance of a provider familiar with sexual health and STI risk
• Does not protect against viral STIs (e.g., HIV, herpes, HPV)—use in combination with other prevention strategies
• Continue regular STI screening every 3 months
What are the possible side effects of Doxycycline?
Common Side Effects:
• Nausea or upset stomach
• Sun sensitivity (photosensitivity)
• Diarrhea
• Mild headache
Less Common:
• Esophageal irritation (take with a full glass of water)
• Yeast infections (oral or genital)
• Allergic reaction (rare)
Precautions:
- Not a substitute for HIV PrEP or HPV protection
- Avoid prolonged sun exposure while taking
- Take with food or water to reduce stomach upset
- Do not use during pregnancy
- Overuse may contribute to antibiotic resistance—intended for high-risk scenarios, not casual use after every exposure